Upload crashes using a background URLSession

[CraigSiemens]

Platform:

• iOS
• tvOS
• MacOS
• watchOS

Swift:

• Yes -> If yes, which version? 4.2.1
• No

sentry-cocoa installed with:

• CocoaPods
• Carthage
• Manually

Version of sentry-cocoa:
4.1.0

---

I have following issue:
If the app is stuck in a state where it crashes on launch, the crashes are never sent to sentry. These types of crashes do appear on Crashlytics.

If your app is running on an OS that supports it (OS X 10.9+, iOS 7.0+), Crashlytics will submit most reports using out-of-process background networking operations. This results in a significant improvement in reliability of reporting, as well as power and performance wins for your users.

Source: Crashlytics.h

Steps to reproduce:

Client.shared = try Client(dsn: "...")
try Client.shared?.startCrashHandler()
Client.shared?.crash()

Actual result:
Crash logs never show up on sentry until the bug is fixed and deployed to the app that is crashing

Expected result:
Sentry should create the network request to upload the crash by using a background URLSession. This would allow the system to handle uploading the crash even if the app is unable to run.

[HazAT]

Hmm, we are using NSURLSession but with ephemeralSessionConfiguration.
Not sure, maybe we want to switch to backgroundSessionConfigurationWithIdentifier.

sentry-cocoa/Sources/Sentry/SentryClient.m

Lines 75 to 76 in 8e4791a

	NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration ephemeralSessionConfiguration];
	NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];

[CraigSiemens]

That would be part of the required change. Background session also don't support completion handlers or data tasks. It would need to be changed to use the URLSessionDelegate methods and upload/download tasks. Using delegate methods would be a bit of work since it's already using completion blocks but switching to upload tasks should be easy since you're already writing a file to disk which is required for background uploads.

https://developer.apple.com/documentation/foundation/url_loading_system/downloading_files_in_the_background
(Also applies to uploads)

[fetzig]

NOTE: crashlytics code https://github.com/firebase/firebase-ios-sdk/search?q=backgroundSessionConfigurationWithIdentifier&unscoped_q=backgroundSessionConfigurationWithIdentifier BOOOM!

[philipphofmann]

This issue could be fixed with fixing #316

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

---

"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀